Logic Instructions: Exclusive-OR

EXOR - Performs a bit-by-bit exclusive OR operation (EX-OR).

An EX-OR gate output is high if either but not both of the inputs is high.

Destination registers are A (EORA) or B (EORB).

All addressing modes are available.

What is the value in A after the following code executes?

ldaa #$bb

eora #$f0

1011 1011 ⊕ 1111 0000 = 0100 1011 = $4b

Notes:

The truth table (A and B are inputs and X is an output) for an EX-OR gate is:A B X 0 0 0 0 1 1 1 0 1 1 1 0The eora instruction performs a bit-by-bit EX-ORing of the bits in the destination register with the operand. In this example bit 0 of register A is EX-ORed with bit 0 of the number f0 hex, and bit 1 of A is EX-ORed with bit 1 of the number f0 hex etc.